Abstract
Purpose of Review This review offers a thorough examination of the pine pathogen Diplodia sapinea , tracing its historical significance from its initial impact on South African non-native Pinus plantations to its recent emergence as a major threat to forests, particularly in Europe. It also highlights recent findings regarding its taxonomic position, genetic studies, and shifts from being perceived as a wound-infecting pathogen to an endophyte in healthy Pinus species that causes disease after stress. Recent Findings Recent years have witnessed a dramatic increase in the damage caused by D. sapinea in natural and planted forests. This escalation is apparently strongly linked to climate change. The pathogen’s previously confused taxonomic position has been clearly resolved in the Botryosphaeriaceae , alongside several sibling species. Diplodia sapinea is now well-understood as an endophyte in healthy trees, which has significant implications for studies aimed at understanding its biology. Importantly, robust techniques including those utilizing genome sequences, are now available for rapid identification and population genetic studies of the pathogen and the factors that drive disease outbreaks. Summary Over the past century, D. sapinea has transitioned from a localized problem in South African non-native plantations to a global threat to both natural and planted forests, particularly in Europe. This review underscores the importance of historical context in understanding the evolution of the pathogen’s impact. It also lays the foundation for future research endeavours, leveraging modern technologies to address key questions surrounding its biology and ecology.